arXiv research

Defines timelike ideal boundary for non-positively curved Lorentzian spaces.

The paper solves the Cauchy problem for Friedrichs systems on specific spacetime manifolds.

Study well-posedness of Faraday tensor problem on specific spacetime manifolds.

We consider the Dirac operator on globally hyperbolic manifolds with timelike boundary and show well-posedness of the Cauchy initial-boundary value problem coupled to MIT-boundary conditions. This is achieved by transforming the problem locally into a symmetric positive hyperbolic system, proving existence and uniquene…

New research proves uniqueness of maximal spacetime boundaries under certain conditions.

Establishes a version of Bartnik's conjecture for Lorentzian length spaces.

New boundary conditions solve Cauchy problem for Dirac operators on spacetimes.

Study timelike bounce in charged null dust collapse, identifying key surfaces.

Proves well-posedness for Einstein equations with totally geodesic timelike boundary condition.

The mass of asymptotically hyperbolic ends and manifolds is analyzed.

Study proves rigidity results for analytic spacetimes without boundary or timelike boundary.

Proves Hadamard states for Dirac fields on manifolds with timelike boundaries.

We define the ideal simplicial volume for compact manifolds with boundary. Roughly speaking, the ideal simplicial volume of a manifold $M$ measures the minimal size of possibly ideal triangulations of $M$ "with real coefficients", thus providing a variation of the ordinary simplicial volume defined by Gromov in 1982, t…

Two different spacetimes can mimic each other's boundary measurements.

The study proves poor ideal three-edge triangulations are minimal for certain 3-manifolds.

The paper constructs a new Ricci-flat metric on almost abelian Lie groups.

We use integrable systems techniques to study the singularities of timelike non-minimal constant mean curvature (CMC) surfaces in the Lorentz-Minkowski 3-space. The singularities arise at the boundary of the Birkhoff big cell of the loop group involved. We examine the behaviour of the surfaces at the big cell boundary,…

The paper studies the past inextendibility of FLRW spacetimes using the VDR asymptote.

Study submanifolds in hyperbolic space, focusing on their boundary and Laplace operator.

We prove that ideal boundary of a 7-systolic group is strongly hereditarily aspherical. For some class of 7-systolic groups we show their boundaries are connected and without local cut points, thus getting some results concerning splittings of those groups.

Globally hyperbolic spacetimes with timelike boundary $(\overline{M} = M \cup \partial M, g)$ are the natural class of spacetimes where regular boundary conditions (eventually asymptotic, if $\overline{M}$ is obtained by means of a conformal embedding) can be posed. $\partial M$ represents the naked singularities and c…

New loops found in universe's timeline, challenging traditional time direction.

This notes explores angle structures on ideally triangulated compact $3$-manifolds with high genus boundary. We show that the existence of angle structures implies the existence of a hyperbolic metric with totally geodesic boundary, and conversely each hyperbolic $3$-manifold with totally geodesic boundary has an ideal…

Given a general pseudo-Anosov flow in a three manifold, the orbit space of the lifted flow to the universal cover is homeomorphic to an open disk. We compactify this orbit space with an ideal circle boundary. If there are no perfect fits between stable and unstable leaves and the flow is not topologically conjugate to …

This paper demonstrates existence for all time of mean curvature flow in Minkowski space with a perpendicular Neumann boundary condition, where the boundary manifold is a convex cone and the flowing manifold is initially spacelike. Using a blowdown argument, we show that under renormalisation this flow converges toward…

We prove that the topology, smooth structure, and metric of a compact Lorentzian manifold with boundary is uniquely determined by data at the boundary. The data consists of the lengths and directions of future-directed once-broken geodesics connecting points on the boundary, which are first timelike and then lightlike.…

Efficient triangulations help in understanding 3-manifold boundaries.

The article studies random infinite ideal hyperbolic polyhedra and their dual graphs, establishing new boundary theories.

Proof of existence for ideal triangulations that normalize fibers in certain 3-manifolds.

We show that when a spacetime $\mathcal{M}(=M \cup \partial M)$ is globally hyperbolic with (possibly empty) smooth timelike boundary $\partial M$, a metrizable topology, the closed limit topology (CLT) introduced by F. Hausdorff himself in the 1950's in set theory, can be advantageously adopted on the Geroch-Kronheime…

Study well-poses Dirac operator problem with APS boundary conditions.

Habiro gave principal ideals of Z[q,q^{-1}] in which certain linear combinations of the colored Jones polynomials of algebraically-split links take values. The author proved that the same linear combinations for ribbon links, boundary links and Brunnian links are contained in smaller ideals of Z[q,q^{-1}] generated by …

Given a compact oriented 3-manifold M in S^3 with boundary, an (M,2n)-tangle T is a 1-manifold with 2n boundary components properly embedded in M. We say that T embeds in a link L in S^3 if T can be completed to L by a 1-manifold with 2n boundary components exterior to M. The link L is called a closure of T. We define …

Proves well-posedness for Einstein equations with specific boundary conditions.

The Frohman Kania-Bartoszynska ideal is an invariant associated to a 3-manifold with boundary and a prime p >3. We give some estimates of this ideal. We also calculate this invariant for some 3-manifolds constructed by doing surgery on a knot in the complement of another knot.

We show that many Lorentzian manifolds of dimension >2 do not admit a spacelike codimension-one foliation, and that almost every manifold of dimension >2 which admits a Lorentzian metric at all admits one which satisfies the dominant energy condition and the timelike convergence condition. These two seemingly unrelated…

We extend the study of the de Rham operator with ideal boundary conditions from the case of isolated conic singularities, as analyzed by Cheeger, to the case of arbitrary stratified pseudomanifolds. We introduce a class of ideal boundary operators and the notion of mezzoperversity, which intermediates between the stand…

We discuss two different in general natural approaches to the ideal closure and ideal boundary of Busemann nonpositively curved metric space. It is shown that the identity map of the space admits surjective continuation from its coarse ideal closure to the weak one. We consider some situations when these closures coinc…

Study shows universal circle isomorphic to flow space ideal boundary.

Starting with an ideal triangulation of the interior of a compact 3-manifold M with boundary, no component of which is a 2-sphere, we provide a construction, called an inflation of the ideal triangulation, to obtain a strongly related triangulations of M itself. Besides a step-by-step algorithm for such a construction,…

Liouville domains have become central objects in symplectic and contact geometry. However, the auxiliary data they involve --- namely, Liouville forms --- and the non-compactness of their completions generate some inconvenience. The notion of ideal Liouville domains is designed to suppress these awkward aspects and to …

Proves well-posedness for Einstein equations with specific boundary data.

The paper proves ideal triangulations and disk unfolding for singular flat surfaces.

We consider hyperbolic manifolds with boundary, which admit an ideal triangulation with n ideal triangles and one edge. We prove that the number of these manifolds is $\exp(n\ln(n)+O(n))$.

The paper finds hyperbolic metrics on surfaces with boundary using combinatorial curvature flows.

Paper proves Luo's conjecture for 3D triangulated manifolds.

We show that the entropy of a hyperbolic group acting on its ideal boundary is closely related to the exponential rate of its growth.

Study of timelike surfaces in Minkowski space with specific geometric properties.